Lose the Cycle by Removing Stock

I have a lightly stocked 40 gallon breeder - about 25 to 30 small guppies, juvies and fry.

I plan to remove about 10 to 15 males and keep them in a separate tank.

I am wondering if the remaining 15 to 20 females, juvies and fry will be enough to keep the cycle going. I expect the population to grow as I expect more fry drops. Just do not want to disrupt cycle of the 40 gallon breeder.

 

The cycle will be fine, you may lose some BB since the bioload won't be as high. But as the fry grow and there's new fry the bioload will increase and the BB colony will also grow to support the load.

 

From what i've read from your previous threads this is a fairly newly cycled 40 breeder but I think it'll maintain the cycle with the removal of some of your stock.best bet is to keep an eye on your parameters and do WC's when needed.

 

You are right that the 40 breeder is newly cycled.

Wondering if I should wait a bit to let the new cycle mature a bit.

Wondering if I should transition a few at a time to balance with additional fry.

Wondering about adding a few bottom feeders at the same time as I remove the males to even out a bit.

 

You don't crash the cycle by removing some of the stock, but of course the population of beneficial bacteria will drop down to the level appropriate to the new bioload. As the population increases with reproduction, so too does the population of bacteria to utilize the increased nutrient supply.

Don't forget, the bioload of a tank containing a single pregnant female doesn't suddenly change when she gives birth. The bioload is the same, and increases gradually as the fry grow and develop.

The only thing to watch out for is a sudden increase in bioload, such as might happen when a large number of new fish is introduced all at once. It will take a couple or few days for the bacterial population to increase enough to catch up with the abrupt jump in bioload, and an ammonia spike may result. Reduced feeding would be recommended during that period.

 

You don't crash the cycle by removing some of the stock, but of course the population of beneficial bacteria will drop down to the level appropriate to the new bioload. As the population increases with reproduction, so too does the population of bacteria to utilize the increased nutrient supply.

Don't forget, the bioload of a tank containing a single pregnant female doesn't suddenly change when she gives birth. The bioload is the same, and increases gradually as the fry grow and develop.

The only thing to watch out for is a sudden increase in bioload, such as might happen when a large number of new fish is introduced all at once. It will take a couple or few days for the bacterial population to increase enough to catch up with the abrupt jump in bioload, and an ammonia spike may result. Reduced feeding would be recommended during that period.

Is reduced feeding for a few days standard procedure for adding fish?

Is there a fish adding guideline that would generally avoid a mini-cycle? Something like a percentage increase.

How long does it take for BB to die off?

 

As far as adding fish that will all depend on what you are going to add. Different fish have different bioloads. Livebearers have a higher bioload then a fish like tetras. I know you had talked about a bottom dweller type fish. If it's some type of Cory Cat you could go with adding 3 this week and 3 more next week. This can all depend on how many male guppies you are removing. Now if you remove 5 or 6 guppies the same day you add the cories I would chance it to add all 6 cories at once since their bioload is much smaller then the guppies. That way there would be a much smaller amount of BB die off after several days. Since the BB will still be getting a source of ammonia even if you don't add fish there will be a die off of some, but it will probably acure at a slower rate. With fry in the tank the load will also increase as they grow, so you will still need to keep an eye on your water parameters.

 

Is reduced feeding for a few days standard procedure for adding fish?

Is there a fish adding guideline that would generally avoid a mini-cycle? Something like a percentage increase.

How long does it take for BB to die off?

I'm sure that if you do a search you could come up with some sort of chart or formula that rigidly lays out numbers and specific procedures for adding new fish. I'm equally sure that strict adherence to such edicts would be a complete waste of time. There are so many variables at play that trying to make hard and fast rules is pointless. It all boils down to a cautious approach, patience, experience and (most importantly) common sense,

Cutting back on feeding for a few days will reduce (but not eliminate) the production of ammonia and thereby reduce the chances if an ammonia spike. The greater the increase in bioload, the more beneficial this would be.

Thinking in terms of percentages is wise. Adding 5 fish to a cycled tank that contains 20 will have a much smaller impact on ammonia levels than adding the same 5 to a similar size tank containing 2. And, of course, the total tank volume comes into play as well; a larger volume of water will dilute a given influx of ammonia much more, quite possibly slowly enough that bacterial populations will increase before levels ever increase dramatically.

Bacteria will die off or increase based on levels of nutrients, but it will also depend upon pH (acidic water inhibits bacterial growth and activity), temperature (warmer water = increased metabolism) and probably many other factors. Under typical aquarium conditions, bacteria can double their population every 24 - 48 hours, Die offs seem to occur much more gradually.

You seem to be looking for black-and-white rules and numbers. I certainly can't provide anything other than general guidelines; I would be suspicious of anyone who claims anything more.

 

I'm sure that if you do a search you could come up with some sort of chart or formula that rigidly lays out numbers and specific procedures for adding new fish. I'm equally sure that strict adherence to such edicts would be a complete waste of time. There are so many variables at play that trying to make hard and fast rules is pointless. It all boils down to a cautious approach, patience, experience and (most importantly) common sense,

You seem to be looking for black-and-white rules and numbers. I certainly can't provide anything other than general guidelines; I would be suspicious of anyone who claims anything more.

I do not believe in strict adherence to anything. Nobody knows anything for sure about anything. But I believe that guidelines are useful in getting a sense of scale. Helpful to get a sense of whether you are way off base or not.